Michelle used a $\$20$ bill to pay for a notebook that only costs $p$ dollars. How much change did Michelle receive from the cashier? Write your answer as an expression. $\$$
Answer: Let's see what happens as the price of the notebook increases: Price of notebook Change received $\${1.00}$ $20 - {1} = 19$ $\${2.00}$ $20-{2} = 18$ $\${3.00}$ $20- {3} = 17$ Price of notebook Change received $\${p}$ $20 -{p} $ The answer: $20-p$